1. Field of the Invention
This invention relates to a new energy attenuation device for a conduit that is adapted to convey liquid under pressure, as well as a system incorporating such a device and a method of attenuating energy in a conduit. The invention is particularly suitable for placement in a conduit conveying liquid under pressure for the attenuation of pressure pulses in the liquid, especially in the hydraulic system of the power steering unit of a vehicle. The invention would also be suitable for other hydraulic fluids.
2. Prior Art Statement
In hydraulic systems where the operating liquid is circulated by a pump, the pulsations of pressure that are generated by the pump are transmitted through the conduits and result in noise and/or vibration being produced by the hydraulic liquid. In the case of power steering fluid in vehicles, such noise and/or vibration is caused, for example, when vehicles are being parked or unparked at idle or very low speeds of movement thereof, such as by barely moving into and out of a parking space or the like while the wheels of the vehicle are being turned by the power steering mechanism thereof. In particular, substantial noise and/or vibration (shudder) can be produced in such a situation when the power steering fluid passes through the power steering mechanism from the fluid pump to the effective steering structure. Further background into this area can be obtained from U.S. Pat. No. 3,323,305, Klees, whereby this U.S. Patent is being incorporated into this disclosure by this reference thereto.
Devices are known for suppressing noise in exhaust gas mufflers. For example, U.S. Pat. No. 4,501,341, Jones, provides two side branch resonators, while U.S. Pat. No. 4,371,053, Jones, provides for an apertured tube in a gas muffler housing. Systems are also known for controlling the resonation of pressure waves in fuel injection systems. For example, U.S. Pat. No. 5,168,855, Stone, passes fluid through check valves that are provided with a flow restriction either directly therein or in a bypass line. U.S. Pat. No. 5,509,391, DeGroot, provides a spool valve assembly for controlling flow between inlet and outlet ports.
Applicants are not aware of any teaching of transferring flow of liquid under pressure from one tube to another as a means of suppressing energy, especially where at least one of the tubes is provided with at least one hole.
It is therefore an object of the present invention to provide an improved device, system and method for attenuating energy in a conduit that conveys liquid under pressure.
This object is realized pursuant to the energy attenuation device of the present invention by providing a conduit means that is disposed in or is part of the liquid-conveying conduit, a restrictor disposed in the conduit and dividing the interior thereof into an inlet chamber and an outlet chamber, and a first tube disposed in one of the chambers, wherein an annular space is formed between the inner peripheral surface of the conduit and an outer peripheral surface of the tube. One end of the tube is connected to and in fluid communication with the restrictor, and the other, free end of the tube is spaced by an open gap from the inlet end of the inlet chamber or the outlet end of the outlet chamber. The tube has at least one aperture in the free end and/or on the peripheral surface thereof for providing fluid communication between the tube and the one chamber.
Accordingly, it is an object of this invention to provide a novel energy attenuation device having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Another object of this invention is to provide a new system incorporating such an energy attenuation device, such a system having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Another object of this invention is to provide a new method of attenuating energy in a conduit conveying liquid under pressure, such a method having one or more of the novel features of this invention as set forth above or hereinafter shown or described.
Other objects, uses, and advantages of this invention are apparent from a reading of the specification in conjunction with the accompanying schematic drawings, which form a part thereof and wherein: